The present invention relates generally to a method and a device for checking the operating condition of an internal combustion engine. More particularly, the invention relates to a method and a device for checking for knocking condition in each individual cylinder of the internal combustion engine.
In automotive vehicles, one common maintenance procedure is detection of knocking in the engine. This monitors the combustion efficiency of the engine. In practice, checking the knocking condition of the engine is conventionally performed by detecting the knocking condition of the engine as a whole instead of that of each individual cylinder. Therefore, there has been no way to detect which cylinder is malfunctioning or knocking. Particularly, in case in which the engine to be checked is a multi-cylinder fuel-injected engine, this checking method is ineffective in detecting knocking in one of the individual cylinders.
At maintenance centers or service shops, it is the conventional practice to service a knocking fuel-injected engine by replacing all the fuel injector nozzles and/or all of the ignition plugs of all cylinders. This leads to unnecessarily expensive maintainance of the engine.
To eliminate such conventional disadvantages, it is necessary to provide a device and/or method for detecting knocking of each individual cylinder. This can be done by detecting engine knocking synchronously with the onset of combustion in each specific cylinder.